Perspectives on Probabilistic Assessment of Systems and Software

International audienceSafety standards in most domains (aeronautics, automotive, industry, nuclear, railway, space) consider software (and more generally, design) as a deterministic artefact. They propose a global rationale combining probabilistic evidence on hardware random failures and deterministic evidence on systematic causes of failures including software. In a context where software is more and more pervasive in all systems, and where it is sometimes advocated that software complexity and size seem to provide some relevance to a probabilistic view of software behaviour, several initiatives suggest to change the way to address software in the global system safety assessment. This is a complex question with many facets. Among them the authors propose to discuss in the paper:-foundations, relevance and limits of probabilistic assessment for software,-relationship between software criticality category, (or class, DAL/SIL/ASIL/SSIL etc.) and probabilistic safety objectives,-the rationale for software diversification and to what extent probabilistic assessment is part of it